Antepartum Risk Factors Research Articles

The newborn at risk of hypoxic-ischemic encephalopathy: a large Italian multicentre retrospective study on antepartum and peripartum risk factors

The newborn at risk of hypoxic-ischemic encephalopathy: a large Italian multicentre retrospective study on antepartum and peripartum risk factors

Antepartum and intrapartum risk factors associated with neonatal metabolic acidosis: a retrospective cohort study

Antepartum and intrapartum risk factors associated with neonatal metabolic acidosis: a retrospective cohort study

Antepartum risk factors and outcomes of massive transfusion for elective cesarean section: a nationwide retrospective cohort study

BackgroundPostpartum hemorrhage is one of the leading causes of maternal mortality and morbidity. The etiology of postpartum hemorrhage exhibits variations in relation to the mode of birth; consequently, risk factors for massive transfusion in elective cesarean section might diverge from those encountered in vaginal birth or emergency cesarean section. The main purpose of this study was to investigate antepartum risk factors of massive transfusion for elective cesarean section.MethodsWe conducted a retrospective cohort study based on data from a nationwide system that collected inpatient medical records from tertiary hospitals in mainland China. We included women who had undergone elective cesarean section from January 2013 to August 2018. Primary outcome was massive transfusion defined as transfusion of more than eight units of red blood cells on the day of childbirth. Candidate risk factors were identified by the 10th revision of International Classification of Diseases Codes of admission diagnoses. The relationship between each factor and massive transfusion was assessed using multivariable logistic regression.ResultsA total of 294,695 women were included and 572 of them received massive transfusion (incidence: 194 per 100,000 elective cesarean sections). Maternal age [adjusted odds ratio (aOR) 1.22; 95% confidence interval (CI) 1.10–1.48], anemia (aOR 1.66; 95% CI 1.34–2.05), thrombocytopenia (aOR 3.54; 95% CI 2.39–5.05), coagulopathy (aOR 25.92; 95% CI 8.59–69.50), hypoalbuminemia (aOR 2.97; 95% CI 1.86–4.53), hepatic dysfunction (aOR 1.65; 95% CI 1.04–2.47), uterine scar (aOR 1.39; 95% CI 1.15–1.67), multiple pregnancy (aOR 2.84; 95% CI 1.74–4.38), polyhydramnios (aOR 2.52; 95% CI 1.19–4.68) and placenta previa (aOR 25.03; 95% CI 21.04–29.77) were associated with massive blood transfusion for elective cesarean section. Among the women receiving massive blood transfusion, 7 (1.2%) died during hospitalization, 126 (22.0%) needed hysterectomy, 25 (4.4%) uterine packing and 57 (10.0%) uterine artery ligation.ConclusionsTen risk factors of massive transfusion were identified in women undergoing elective cesarean section. Our findings may facilitate blood products preparation and provide opportunities for applying prophylactic strategies prior to cesarean section for women at high risk of massive transfusion.

Delivery room resuscitation and short-term outcomes in very preterm infants: a multicenter cross-sectional study in China.

To explore the risk factors of delivery room (DR) resuscitation and assess the association of DR resuscitation with neonatal outcomes in very preterm infants (VPIs). A multicenter retrospective cross-sectional study included VPIs with gestational age (GA) <32 weeks born between January, 2022 and June, 2023 and admitted to neonatal intensive care units of six tertiary hospitals in Shenzhen within 24 h after birth. They were divided into routine care group, positive-pressure ventilation (PPV) group, and endotracheal intubation (ETT) group based on the highest intensity of resuscitation received at birth. The association of antepartum and intrapartum risk factors and short-term outcomes with the intensity of DR resuscitation was evaluated. Of 683 infants included in this study, 170 (24.9%) received routine care, 260 (38.1%) received bag and mask ventilation or T-piece ventilation and 253 (37%) received ETT. Among the antepartum and intrapartum factors, exposure to antenatal steroids (ANS) decreased the likelihood of ETT. Increasing GA decreased the likelihood of receiving a higher level of DR resuscitation. Among the neonatal outcomes, increasing intensity of DR resuscitation was associated with a raise in the risk of Bronchopulmonary dysplasia. Higher levels of DR resuscitation were associated with the risk of early-onset sepsis. ETT was significantly associated with an increased risk of death. Among VPIs, low GA and no ANS use increased the risk of high-intensity DR resuscitation interventions; and those who receiving ETT were associated with an increased risk of adverse clinical outcomes.

Uncommon Organisms in Neonatal Meningitis: Two Case Reports

These case reports describe two neonates, born at term, diagnosed with bacterial meningitis and septicemia caused by uncommon organisms. The clinical presentation, diagnostic reasoning, national guidelines, hospital course, and follow-up are discussed. Meningitis is among the differential diagnoses when there is a concern for neonatal sepsis. Concern for sepsis can arise from a variety of antepartum, intrapartum, and postpartum risk factors and present with a variety of symptoms. Neonatal sepsis is a significant cause of mortality, with 750,000 infant deaths annually. Effective treatment of neonatal sepsis requires timely diagnosis and tailored antimicrobial therapy that targets the causative pathogens.

Cesarean Scar Defect (Niche) Risk Factors: A Prospective Study on Indonesian Women

Introduction: Niche or cesarean scar defect is a complication of a cesarean section that has long-term implications for both obstetrics and gynecology. The rate of niche is believed to be increasing with the high number of cesarean sections. This study assesses the risk factors for niche development after cesarean section. Methods: A prospective cohort study was conducted on women who underwent cesarean section at the Haji Adam Malik General Hospital Medan between August 2020 and August 2022. Niche was assessed six weeks after cesarean section using transvaginal ultrasonography. The primary outcome was the presence of a niche. The antepartum, intrapartum and postpartum risk factors were analyzed for niche development. A logistic regression model was used to assess independent risk factors from the bivariate analysis. Results: There were 280 patients enrolled in this study. The prevalence of niche was 44.3% by using transvaginal ultrasound. There was no significant relationship between maternal age, gestational age, parity, nutritional status based on upper arm circumference, hypertension in pregnancy, anemia status, surgical indications, duration of surgery, volume blood loss, and puerperal infection to niche development (P &gt; 0.05). The independent risk factors for niche development were Cervical dilatation &gt; 4 cm (P = 0.035; RR = 1.75), locking suture technique (P = 0.015; RR = 13.81), non-closure vesicouterine folds (P = 0.04; RR = 0.14) and a retroflexed uterus (P = 0.001; RR = 0.039). Conclusion: Cervical dilatation &gt; 4 cm, locking suture technique, non-closure vesicouterine folds, and a retroflexed uterus are risk factors for niche development after CS.

Develop a web-based system using the Naïve Bayes algorithm to predict asphyxia neonatal

Introduction: Most cases of perinatal asphyxia are caused by conditions unrelated to labor. When asphyxia occurs during childbirth, it is usually caused by an obstetric emergency that was not detected during pregnancy. It is essential to prevent asphyxia by identifying the incidence of asphyxia during pregnancy. Several studies have been conducted to identify asphyxia problems developing by predictive models. However, there has been no development of a system for predicting birth asphyxia during pregnancy and carried out in primary health facilities.Purpose: Develop a web-based system using the Naïve Bayes (NB) algorithm to predict asphyxia neonatal using a dataset of antepartum risk factors in primary health facilities.Methods: This study employed research and development, which consists of 4 stages, namely literature study, development stage, expert validity, and trial.Results: A system that health workers in primary health facilities can use to predict asphyxia neonatal and recommend referrals for determining the place of childbirth has been successfully created. The system performance test predicted asphyxia neonatal with all NB evaluation values reaching more than 98%, and the prediction accuracy in the respondent test included in the High Accuracy category (MAPE value 9.06%).Conclusion: The development of a web-based system using the NB algorithm has been proven to be able to predict asphyxia neonatal and can be implemented for health workers as an effort to anticipate delays in handling cases of asphyxia neonatal because of the predicted results along with recommendations for focusing mothers with the risk of babies born asphyxia to find out possible childbirth places.

Incidence and Antepartum Risk Factors of Severe Postpartum Haemorrhage in Anaemic Pregnant Women in Lagos, Nigeria: A Secondary Cohort Analysis.

The magnitude and risk factors for postpartum haemorrhage (PPH) have been extensively investigated, although little is currently known about the incidence and predictors of severe PPH, specifically among women affected by prenatal anaemia in Nigeria. The study determined the incidence and antepartum risk factors of severe PPH in anaemic pregnant women in five health institutions in Lagos, Southwest Nigeria. A secondary analysis was performed using the data of pregnant women with anaemia from the "Predict-PPH" study that was conducted between January and June 2023. This study included n=570 pregnant women affected by anaemia who gave birth in five hospitals in the Lagos metropolis of Nigeria. The study outcome was severe PPH, defined as an estimated blood loss of at least 1000 mL within 24 hours of childbirth. A backward stepwise conditional approach in a multivariable logistic regression model was utilised to identify the independent risk factors for severe PPH in anaemic pregnant women. Of the 570 women with prenatal anaemia enrolled in the primary study, 42 (7.4%) had severe PPH. The identified independent risk factors for severe PPH were maternal obesity (adjusted OR = 3.85, 95% CI = 1.85-8.02), antepartum haemorrhage in index pregnancy (adjusted OR = 2.98, 95% CI = 1.29-6.90), uterine fibroids (adjusted OR = 6.10, 95% CI = 2.39-15.52), delivery gestational age ≥39 weeks (adjusted OR = 2.62, 95% CI = 1.23-5.56), and delivery by caesarean birth (adjusted OR = 16.75, 95% CI = 5.81-48.31). About one in 13 anaemic pregnant women enrolled in the study developed severe PPH during childbirth. Maternal obesity, antepartum bleeding in the current pregnancy, co-existing uterine fibroids in pregnancy, delivery gestational age beyond 38 weeks, and caesarean birth in the current pregnancy were factors that were significantly associated with severe PPH in anaemic pregnant women. These findings underscore the importance of increased vigilance during both the antenatal and peripartum periods to identify women with these risk factors for the initiation of timely interventions to prevent severe PPH.

1187 Placental abruption and antepartum hemorrhage delivery hospitalization trends, risk factors, and outcomes

1187 Placental abruption and antepartum hemorrhage delivery hospitalization trends, risk factors, and outcomes

Placental pathology in perinatal asphyxia: a case-control study.

Placentas of term infants with birth asphyxia are reported to have more lesion such as maternal vascular malperfusion (MVM), fetal vascular malperfusion (FVM) and chorioamnionitis with fetal response (FIR) than those of term infants without birth asphyxia. We compared the placental pathology of asphyxiated newborns, including those who developed hypoxic-ischemic encephalopathy (HIE), with non-asphyxiated controls. We conducted a retrospective case-control study of placentas from neonates with a gestational age ≥ 35 weeks, a birthweight ≥ 1,800 g, and no malformations. Cases were asphyxiated newborns (defined as those with an umbilical artery pH ≤ 7.0 or base excess ≤ -12 mMol, 10-minute Apgar score ≤ 5, or the need for resuscitation lasting >10 min) from a previous cohort, with (n=32) and without (n=173) diagnosis of HIE. Controls were non-asphyxiated newborns from low-risk l (n= 50) or high-risk (n= 68) pregnancies. Placentas were analyzed according to the Amsterdam Placental Workshop Group Consensus Statement 2014. Cases had a higher prevalence of nulliparity, BMI>25, thick meconium, abnormal fetal heart monitoring, and acute intrapartum events than controls (p<0.001). MVM and FVM were more frequent among non-asphyxiated than asphyxiated newborns (p<0.001). There was no significant difference in inflammatory lesions or abnormal umbilical insertion site. Histologic meconium-associated changes (MAC) were observed in asphyxiated newborns only (p= 0.039). Our results confirm the role of antepartum and intrapartum risk factors in neonatal asphyxia and HIE. No association between neonatal asphyxia and placental lesions was found, except for in the case of MAC. The association between clinical and placental data is crucial to understanding and possibly preventing perinatal asphyxia in subsequent pregnancies.

Risk of obstetric anal sphincter injuries at the time of admission for delivery: A clinical prediction model.

To develop and validate a model to predict obstetric anal sphincter injuries (OASIS) using only information available at the time of admission for labour. A clinical predictive model using a retrospective cohort. A US health system containing one community and one tertiary hospital. A total of 22 873 pregnancy episodes with in-hospital delivery at or beyond 21 weeks of gestation. Thirty antepartum risk factors were identified as candidate variables, and a prediction model was built using logistic regression predicting OASIS versus no OASIS. Models were fit using the overall study population and separately using hospital-specific cohorts. Bootstrapping was used for internal validation and external cross-validation was performed between the two hospital cohorts. Model performance was estimated using the bias-corrected concordance index (c-index), calibration plots and decision curves. Fifteen risk factors were retained in the final model. Decreasing parity, previous caesarean birth and cardiovascular disease increased risk of OASIS, whereas tobacco use and black race decreased risk. The final model from the total study population had good discrimination (c-index 0.77, 95% confidence interval [CI] 0.75-0.78) and was able to accurately predict risks between 0 and 35%, where average risk for OASIS was 3%. The site-specific model fit using patients only from the tertiary hospital had c-stat 0.74 (95% CI 0.72-0.77) on community hospital patients, and the community hospital model was 0.77 (95%CI 0.76-0.80) on the tertiary hospital patients. OASIS can be accurately predicted based on variables known at the time of admission for labour. These predictions could be useful for selectively implementing OASIS prevention strategies.

The evaluation of the antepartum and intrapartum risk factors in predicting the risk of birth asphyxia.

This study aimed to determine the related antepartum and intrapartum factors of birth asphyxia among neonates born in a tertiary referral hospital. A total of 45 singleton pregnant women who delivered live births with a gestational age of ≥35 weeks and their neonates who suffered from birth asphyxia from June 2016 to June 2021 were included in this retrospective study. Data regarding maternal demographic features, maternal laboratory values, pregnancy complications, and obstetric and neonatal outcomes were collected. Significant risk factors associated with birth asphyxia were nulliparity (odds ratio [OR]=5.357, 95% confidence interval [CI]=2.169-24.950, p=0.001), placental abruption (OR=8.667, 95% CI=2.223-33.784, p=0.002), intrauterine growth restriction (OR=1.394, 95% CI=1.109-8.631, p=0.012), the prolonged second stage of labor (OR=6.121, 95% CI=2.120-17.595, p=0.001), meconium-stained amniotic fluid (OR=7.615, 95% CI=2.394-24.223, p=0.001), bloody amniotic fluid (OR=9.423, 95% CI=2.885-35.232, p=0.001), the presence of FHR category II (OR=12.083, 95% CI=7.081-48.849, p <0.001) and FHR category III before labor (OR=15.500, 95% CI=8.394-56.176, p <0.001). We identified that nulliparity, placental abruption, intrauterine growth restriction, the prolonged second stage of labor, meconium-stained or bloody amniotic fluid, and FHR tracings categories II and III were significantly associated with birth asphyxia.

Risk factors of preterm babies: Regarding to gestational age, maternal medical history, delivery mode and influences

Background: The World Health Organization defines preterm birth as any birth before 37 completed weeks of gestation or fewer than 259 days since the first day of woman’s last menstrual period. Objectives: To identify antepartum, intrapartum, and fetal risk factors of preterm delivery and their effect on neonatal survival. Methods: A cross-sectional study conducted on 185 neonates delivered preterm in neonatal intensive care unit of Misurata Central Hospital, Libya. Retrospective analysis of hospital recorded over a period of one year have be done, that from January to December 2019. Data include the babies’ and mother demographic char­acteristics; antepartum, intrapartum, postpartum risk factors; and APGAR scores of such babies at 1 min; and survival for preterm baby were analyzed. Results: Majority of cases are born to mothers aged 18-35 years (80%) and that is not significant P≥0.05, while the mode of delivery, C\S was 70% and Antepartum risk factors infection was took the upper hand 40%, and that is highly statistically significant. There is no significant correlation regarding gestational age and gender where P≥0.05, while the weight and APGAR score are highly significant relationship with gestational age (P˂0.05) as shown in. Conclusion: Majority of cases are borne to mothers aged 18-35 years while the mode of delivery, vaginal delivery was the upper hand in extreme preterm while C\S is of priority of others. Antepartum risk factors were took the upper hand 40%. Male and female equally at risk to be delivered prematurely. APGAR score and birth weight improved with increase the gestational age. The mechanical support is one of the early respiratory in extreme babies that improve survival rate.

Risk factors for seizures in the vigorous term neonate: A population-based register study of singleton births in Sweden.

BackgroundNeonatal seizures have been associated with increased mortality and impaired neurodevelopment and, knowledge about risk factors may be useful for prevention. Clear associations have been established between labor-related risk factors and seizures in asphyxiated neonates. However, there is limited information about why some vigorous term-born infants experience seizures.ObjectivesOur aim was to assess antepartum and intrapartum risk factors for seizures in vigorous term-born neonates.MethodsThis was a national cohort study of singleton infants born at term in Sweden from 2009–2015. Vigorous was defined as an Apgar score of at least 7 at 5 and 10 minutes. Data on the mothers and infants were obtained from the Swedish Medical Birth Register and the Swedish Neonatal Quality Register. A diagnosis of neonatal seizures was the main outcome measure and the exposures were pregnancy and labor variables. Logistic regression analysis was used and the results are expressed as adjusted odds ratios (aOR) with 95% confidence intervals (CI).ResultsThe incidence of neonatal seizures was 0.81/1,000 for 656 088 births. Seizures were strongly associated with obstetric emergencies (aOR 4.0, 95% CI 2.2–7.4), intrapartum fever and/or chorioamnionitis (aOR 3.4, 95% CI 2.1–5.3), and intrapartum fetal distress (aOR 3.0, 95% CI 2.4–3.7). Other associated intrapartum factors were: labor dystocia, occiput posterior position, operative vaginal delivery, and Cesarean delivery. Some maternal factors more than doubled the risk: a body mass of more than 40 (aOR 2.6, 95% CI 1.4–4.8), hypertensive disorders (aOR 2.3, 95% CI 1.7–3.1) and diabetes mellitus (aOR 2.6, 95% CI 1.7–4.1).ConclusionA number of intrapartum factors were associated with an increased risk of seizures in vigorous term-born neonates. Obstetric emergencies, intrapartum fever and/or chorioamnionitis and fetal distress were the strongest associated risks. The presence of such factors, despite a reassuring Apgar score could prompt close surveillance.

Neonatal Encephalopathy in the Term Newborn

Perinatal brain injury is the third leading cause of child mortality globally. Purpose: Evaluation of perinatal risk factors for encephalopathy in neonates in order to prevent deaths and disabilities Method: This is a prospective, case-control study conducted in the Maternity Hospital “K. Gliozheni” during the time period 2012 – 2016. 65 newborns at term ≥37 weeks diagnosed with encephalopathy according to the Thompson classification &gt;5 within 12 hours of birth were compared with a control group, infants without encephalopathy in a 1:1 ratio selected casual and gender-appropriate. Results: Total antepartum risk factors were found in (70.8%) of cases and (18.5%) of controls (p&lt;0.01). Sentinel events were found in 38.5% of cases and in 9.2% of controls. (p&lt;0.01). Acute intrapartum events in total were found in (38.5%) of cases and (9.2%) of controls (p&lt;0.01). 43.1% of babies had a combination of antepartum and intrapartum factors (p&lt;0.01). Significant and independent predictive factors of risk for neonatal encephalopathy resulted: from maternal factors, mother’s age &gt;35 years (p=0.03). Of the intrapartum factors: pregnancy with twins (p&lt;0.01), hypertension/preeclampsia (p&lt;0.01), non-reactive FHR before delivery (p&lt;0.01). MEDICUS No. 6, ISSUE 2/ 2022 103 From intrapartum factors: breech birth (p=0.01), emergency cesarean section (p=0.01), meconial amniotic fluid (p=0.02), prolonged birth (p=0.01). Conclusion: Knowledge of perinatal risk factors associated with neonatal encephalopathy is essential for developing interventions to prevent neonatal death and disability.

Prediction of Shoulder Dystocia using Third Trimester Ultrasound and Clinical Data

Shoulder dystocia (SD) is a rare but life-threatening complication of vaginal delivery, occurring in approximately 0.2 to 3.0% of births. Prior studies identified numerous antepartum and intrapartum risk factors. Ultrasound (US) findings have been suggested as an adjunct to aid in the prediction of SD, however, prior studies have been inconsistent in their findings and were limited by low sensitivity and positive predictive values. We hypothesize that a combination of clinical and third trimester US parameters can be used to create a reliable prediction model for SD.

Clinical Validation of a Dynamic Obstetric Hemorrhage Risk Assessment Tool at an Urban Safety-Net Hospital

Obstetric hemorrhage is the leading cause of maternal mortality worldwide. There are emerging risk assessment tools with labor factors to guide prenatal pre-transfusion testing. In this study, we describe a dynamic risk assessment tool that includes antepartum and intrapartum risk factors, and assess its efficacy in predicting obstetric hemorrhage and hemorrhage requiring transfusion in an urban safety-net hospital.

Near-Miss Incidents in Obstetric Patients Admitted to an Intensive Care Unit of a Tertiary Care Center in Eastern India: A Retrospective Cohort Study.

AimObstetric patients presenting to the intensive care units (ICU) with or without underlying medical or surgical comorbidities can be a challenge to both the treating obstetrician and the intensivist. They occasionally present with near-miss events which if left untreated, can result in death.ObjectivesTo study the prevalence, indications of ICU admissions, near-miss events, and their effect on mortality in obstetric and puerperal patients.Material & methodsWe conducted a retrospective analysis of the health records of all the obstetric and puerperal patients (pregnant and until 6 weeks postpartum) admitted to our tertiary care hospital from January 2019 to December 2020. Patient demographic characteristics, obstetric, surgical, and medical conditions, acute physiology, and chronic health evaluation (APACHE) II scores, organ failures, treatment, ICU and hospital length of stay, and mortality outcomes were studied.ResultsA total of 22 obstetric patients were admitted to the ICU during the above study period. Mean age was 28.7 ± 6.24 years, mean gestation was 34.4 ± 6.61 weeks, mean APACHE II score was 12.68 ± 5.67, median ICU length of stay was 5 days, and median duration of hospital length of stay was 10 days. The antepartum risk factors such as severe preeclampsia (27%), antepartum bleeding (14%), and postpartum complications like postpartum haemorrhage (33%), sepsis with multiorgan failure (25%) are the commonest indications that resulted in ICU admission.ConclusionHigher APACHE II scores at the time of ICU admission, prolonged ICU, and hospital length of stay may be associated with high maternal mortality.

Hypoxic ischemic encephalopathy in offspring of immigrant women in Sweden: A population-based cohort study.

One in four women giving birth in Sweden is foreign-born. Immigrant status has been suggested as a risk factor for adverse perinatal outcomes. It is not known if infants to foreign-born women have an increased risk of severe birth asphyxia, or which factors might mediate such association. A population-based cohort study of 726730live births at 36weeks of gestation or more in Sweden in 2009-2015. The exposure was maternal country of birth, grouped according to the World Bank country classification: low-, lower-middle, upper-middle, and high-income economies. The main outcome was neonatal hypoxic ischemic encephalopathy (HIE). The outcome was estimated by severity and classified as non-hypothermia-treated HIE, representing mainly mild cases, and hypothermia-treated HIE, representing moderate to severe cases. A secondary outcome was low Apgar score at 5minutes, defined as <7 or <4. Odds ratios with 95% CI were calculated, using Swedish-born women as the reference. Structural equation modeling was used to investigate potential mediation of known antepartum risk factors. A total of 854 infants were diagnosed with HIE and 398 received therapeutic hypothermia. Offspring of mothers born in low-income countries had the highest incidences of HIE and low Apgar score, with an incidence of therapeutic hypothermia of 1.1 per 1000. Compared with offspring of Swedish-born mothers, these neonates had an almost two-fold increased risk of HIE, with or without hypothermia treatment (odds ratio 1.7; 95% CI 1.2-2.7 and odds ratio 1.7; 95% CI 1.2-2.6, respectively), and a 2- to 3-fold increased risk of low Apgar score. The structural equation model analysis indicated an exclusive direct effect of country of birth on HIE. Factors reflecting socio-economic status mediated a small proportion of the risk of Apgar score <7 at 5minutes. Offspring of women born in low-income countries had associations with severe birth asphyxia, with increased risk of both HIE and low Apgar score at 5minutes. The associations seemed only to be marginally mediated by other antepartum factors. The associations are complex and further studies are needed to find explanatory and potentially preventable factors.

Is the increase in postpartum hemorrhage after vaginal birth because of altered clinical practice?: A register-based cohort study.

To identify risk factors for severe postpartum hemorrhage (PPH) ≥1000ml in women giving birth vaginally. A register-based cohort study including women with singleton pregnancies giving birth vaginally at term to a live-born child at Aarhus University Hospital, Denmark, from January 1, 2004, to December 31, 2012. Logistic multivariable regression was used to analyze data. In 31837 births, 1832 women (5.7%) experienced severe PPH. Maternal age, smoking during pregnancy, and prepregnancy body mass index did not increase the risk of severe PPH. However, nulliparous and multiparous women with a previous cesarean birth had an increased risk of severe PPH. Antepartum and intrapartum risk factors for severe PPH included gestational age >40weeks, induction of labor, augmentation of labor, irregular fetal position, instrumental birth, and birthweight >4000g. In particular, the combination of induction and augmentation of labor doubled the risk of severe PPH. Among genital tract tears, vaginal tears >3cm were associated with the highest risk of severe PPH. Maternal characteristics did not increase the risk of severe PPH, except for nulliparous and multiparous women with a previous cesarean birth. Obstetric interventions such as induction of labor, augmentation of labor, and a birthweight higher than 4000g increased the risk of severe PPH. Larger vaginal tears presented the highest risk of severe PPH. Clinical practice with rigorous indications for obstetric interventions and timely identification and management of genital tract tears may reduce risk of severe PPH.